Polarity changer



Nov. 29, 1949 I I I J. A. MAS

POLARITY CHANGER Filed Fob. 22, 1945 21 17 1 2 w 19 v 7\ i 24 M22 M E 2, A1 I an 21;

INVENTOR. JOSE A. MAS BY W? 77%22 Patented Nov. 29, 1949 POLARITY CHANGER Jose A. Mas, Indianapolis, Ind., assignor, by mcsnc assignments, to Cornell-Dubilier Electric Corporation, South Plainilcld,

of Delaware N. 1., a corporation Application February 22, 1945. Serial No. 579,21? 1 Claim. (01. 321-49) My invention relates to improvements in' vibrator interrupter circuits and more particularly to vibrator interrupter circuits, which through the medium of the vibrator interrupter are adapted to alternately change the polarity of a unidirectional current or direct current to deliver to the load an alternating current of approximately the same or diilerent voltages.

In polarity changers of the prior commercial art, it has been customary to provide a commutating condenser, in the circuit adapted to be controlled by the vibrating interrupter, and generally across the terminals of the load. One difilculty which has been experienced in such an arrangement is the destructive eflect of such upon the contacts of the vibrating interrupter as well as upon the condenser itself. This is primarily noticeable in instances where the polarity changers are operating under no load conditions. Heretofore, the rate of discharge of the commutating condenser has been determined only by the load resistance and under no load conditions and therefore in the absence of load resistance, the condenser is unable to discharge during the off contact interval of the vibrating interrupter, which necessarily results in an exceedingly. high current through the vibrating contacts or points on the make contact interval.

It is one of the objects of my invention to provide means whereby the make current, through the contact points, may be reduced to the minimum, even though there is no load resistance on the polarity changer, and thus reduce the destructive effect on the contact points of the vibrating interrupter to a minimum.

It is a further object of my invention to provide a means whereby the condenser may discharge during the off contact interval, even though there is no load resistance in the circuit and thus reduce to the minimum the make current through the vibrator currents and through the condenser.

A further object of my invention is to provide means whereby at the interval of the make contact of the contacts of th interrupter the current is substantially zero.

It is a further object of my invention to provide a vibrator interrupter polarity changer means whereby on the make contact of the interrupter contacts, the contact current is reduced to a minimum under all conditions, whether full load, no load, or a variable load.

For the purpose of disclosing my invention, I

have illustrated certain embodiments thereof in the accompanying drawings, in which:

Fig. l is a diagrammatic view of a circuit arrangement of the interrupter system embodying my invention;

Fig. 2 is a diagrammatic view of a circuit embodying my invention, wherein a plurality of contacts are provided to provide current division, and thus reduce the current carried by each contact; and

Fig. 3 is a diagrammatic view embodying my invention disclosing substantially the same subject matter, as disclosed in Fig. 2, with the exception that I have provided means for stepping up the output of the voltage.

Referring to the interrupter systems disclosed in the accompanying drawings, in Fig. 1 there is provided aninterrupter, comprising a vibrating reed I carrying oppositely mounted contacts 2 and 3. This reed vibrates between relatively stationary contacts 4 and 5 disposed on opposite sides of the reed and adapted to be engaged respectively during the vibration of the reed by contacts 2' and 3. The reed is driven through the medium of an electro magnet having an energizing coil 6, one terminal of which is connected with a relatively stationary contact '8 adapted to have make and break engagement with a driver contact 8. The opposite terminal of the coil 6 is connected to a source of direct current supply, which in the present instance is disclosed as a battery 9.

A second reed l0, having contacts ii and i2 similar to contacts 2 and 3 on the reed l, is provided and this reed vibrates between oppositely disposed relatively and H. The two reeds i and ID are mechanically connected, but electrically separated, so that they will vibrate in unison under the driving efiect of the driving coil 6.

The reed i is connected to one terminal of the battery 9 and the reed I0 is connected to the opposite terminal of the battery 9. Contacts I and I! are connected respectively to opposite terminals adapted for connection with the load, and contacts 5 and It are similarly connected to the opposite terminals adapted for connection with the load, the arrangement being that contacts l and I are connected to the same side of the load and'contacts 5 and ii are connected to the opposite side of the load.

Connected across the load is a condenser I I and in parallel with the condenser, and across the terminal of the load is connected a linear reactor ll.

stationary contacts I! In operation as the vibrating reeds i and I! operate between their respective sets of stationary contacts when the reeds swing in their contacts 2 and Ii with contacts 4 and I3. current will be delivered from the source of DC power, the battery 9, through the load in one direction.

As soon,'however, as the reed vibrates in the opposite direction to engage contacts 3 and I2 with contacts 5 and It, the polarity of the current through the load will be reversed. The unidirectional current from battery 9 is thus converted into alternating current through the load.

During the on contact interval, the condenser 15 will be drawing energy from the circuit receiving the charge. Also during this contact interval, the linear reactor likewise draws energy from the circuit. During the of! contact period, this energy is used to discharge the condenser l8 and to charge the condenser to an opposite polarity so that when the make contact is made between the opposite contacts, or on the other side of the vibrating reed, the condenser is already charging at its proper polarity, thereby reducing the current burden on the contact to the minimum. I have found, from actual experience, that it is possible to swing the condenser during the oil! contact interval to an equal voltage and opposite polarity, resulting substantially in a zero make current, thereby reducing the make current ofv the contacts of the vibrator and particularly during no load conditio'ns, or during under load conditions, to a min- In the arrangement shown in Fig. 2, I have illustrated my invention as used in connection with a balanced interrupter system, wherein I have provided parallel sets of contacts for dividing the current to improve the life of the contacts. In this arrangement, the interrupter comprises the oppositely disposed sets of contacts l1 and 18 with the vibrator reed l operating between them and provided with contacts I! and 20 and a second set of contacts comprising the oppositely disposed contacts 21 and 22,

between which the contacts 23 and 24 on the reed I vibrate.- Contacts l1 and 2| may be referred to as the rebound contacts and contacts l8 and 22 may be referred to as the magnet side contacts. Likewise, associated with the reed I0 is a set of oppositely disposed contacts 25 and 26, between which the contacts 21 and 28 on the reed i0 vibrate and a second set of oppositely disposed contacts 29 and 30, between which the contacts 3| and 32 on the reed l0 vibrate. Contacts 25 and 29 may be referred to as the rebound contacts and contacts 26 and 30 may be referred to as the magnet side contacts. The vibrating reeds l and ID are connected with the battery 9, as in Fig. l. The contacts I! and 2| are respectively connected to the opposite terminals of the winding 33 of a linear inductance 24, a center tap 35 of this winding being connected to one terminal of the load. Likewise, the contacts 26 and 30 are similarly connected to the opposite terminals of the winding 33 of the balancing inductance 34. Contacts l8 and 22 are respectively connected to the outer terminals oi the winding 36 of a balancing inductance a 31, likewise having a center tap 38 connected the opposite side of the load. Similarly, contacts 25 and 29 are connected to the opposite terminals of the winding '38.

Across the contactsfl'l and i8 and also across the contacts 25 and 28 is connected a condenser or capacitor 39 and a similar condenser or capacitor 40 is connected across contacts 2| and 22 and similarly across the contacts 29 and 30. Across the load is connected 9. linear reactor ll, similar in efiect and operation to the reactor l8 inthe arrangement shown in Fig. 1.

In the structure illustrated in Fig. 3, I have shown an arrangement whereby I am enabled to step up the output voltage through the medium of extra turns 42 and 43 on the'liner reactor or auto, transformer ll. In other respects, the arrangement shown in Fig. 3 is the same as that shown in Fig. 2.

I claim: Y An electrical system for converting current from a direct current source into alternating current, said system comprisinga first vibratory interrupter having two sets olparallel contacts, with each set comprising oppositely disposed magnet side and rebound contact means and vibratory contact means operating therebetween and connected to one side of direct current source, a second vibratory interrupter having two sets of parallel contacts, with each set comprising oppositely disposed magnet side and rebound contact means and vibratory contact means operating therebetween and connected to the opposite side of said direct current source, a capacitor connected across the oppositely disposed contact means of each of said vibratory interrupters, balancing inductance means having a first balancing winding with a center tap connected to one side of an output circuit and dividingsaid first balancing winding into halves, the opposite halves of the winding being respectively to the rebound parallel contacts of the first vibratory interrupter and to the magnet side parallel contacts of the second vibratory interrupter, a second balancing winding with a center tap connected to the other side of the output circult and dividing said windings in halves; the

opposite halves of said second balancing winding being respectivelyconnected to the magnet side contacts of the first vibratory interrupter and to the rebound contacts of the second vibratory interrupter, and a linear reactor connected across the center taps of said balancing inductance. Jose: A. MAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS Number Name Date 1,296,269 Crawford et al Mar. 4, 1919 2,036,399 Comstock Apr. '7, 1936 2,194,288 Aust Mar. 19, 1940 2,258,303 Schmidt et al Oct. '7, 1941 2,291,069 Brown July 28, 1942 2,322,597 Short June 22, 1943 2,327,575 Brown Aug. 24, 1943 2,327,577 Brown Aug. 24, 1943 2,338,080 Brown Dec. 28, 1943 numbered patent requiring correction as follows:,

5 Certificate of Correction Patent No. 2,489,656 November 29,1949

JOSE A; MAS

It is hereby certified that error. appears in the printed speeificntion of the above 7 Column 4, line 41, after the word respectively insert connected;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the casein the Patent Ofiice.

' Signed and sealed this 11th dey of April, A.'D. 1950. 9

THOMAS F. MURPHY,

Assistant C'ommiuioncr of Pam 

